Joe Biden had a moving, emotional interview with Stephen Colbert Thursday night on the “Late Show.” The sitting vice president opened up to the talk show host about grief and their shared experience of personal loss.

Mr. Biden’s son Beau, former Delaware attorney general, died in May. At times, Biden seemed to be fighting tears as he talked about struggling to cope with Beau’s absence.

“I was a hell of a success. My son was better than me. He was better than me in every way,” he said.

Beau never complained about health problems, according to Biden. Instead, he asked his father if he – the VP – was going to be all right. Beau insisted the family not tell anyone he had won the Bronze Star while serving as a major with the Army National Guard in Iraq. The senior Biden said that his son had requested a fake name tag on his uniform so no one would think he was getting special treatment.

Recently, the vice president was meeting with service members as part of his regular duties. From the back of the room, one person spoke up, saying only, “Maj. Beau Biden, Bronze Star. Served with him in Iraq.”

“I lost it,” Biden said.

In 1972, just after his initial election to the Senate, Biden’s first wife and infant daughter were killed in an auto accident. Mr. Colbert, when he was 10 years old, lost his father and two brothers in a plane crash.

Biden pointed this out, saying that Colbert also understood suffering. The host replied, “My mom had an expression: What’s the use of being Irish if you don’t know life can break your heart?”

On the obvious subject – the elephant in the room that’s a donkey, as Colbert put it – Biden seemed reluctant about the prospect of running for the presidency.

It’s such a difficult and important job that you owe the country your full devotion if you win, Biden said.

“I’d be lying if I said I knew I was there.... Nobody has a right in my view to seek that office unless they are willing to give it 110 percent of who they are,” Biden said.

What’s the take-away there? That Biden is struggling with the pressure he’s getting to jump into the race, perhaps. Our view has long been that he’s running now, in the sense of gauging support and opposition and keeping his options open. But he’s run twice before, and grief isn’t a platform. It is very close to too late for him to take the next step and openly challenge Hillary Clinton.

It’s not just about putting an organization together. Filing deadlines for primaries are coming up. If a candidate hasn’t officially declared by November, he or she begins to forfeit possible delegate votes, in essence, as this Brookings analysis shows.

If he does run, though, he’ll have at least one huge supporter in the media. Colbert treated Jeb Bush well in his first night’s show, but he was much warmer and more solicitous of the sitting VP.